In the field of hair care, compositions based on anionic, non-ionic and amphoteric surfactants are commonly used. They are applied to wet hair and foam is generated by massage or friction with the hands which allows, after rinsing with water, elimination of the dirt initially present.
If these formulations have good washing power, their intrinsic cosmetic properties however remain limited, particularly because of the relatively aggressive nature of the treatment to which they subject the hair: it can cause more or less marked damage to the capillary fibre, including the gradual elimination of lipids and proteins contained in the hair.
It is also necessary to use additives whose function is to improve the cosmetic properties of the hair formulations in which they are incorporated. Among these properties, “the styling effect” is one that is sought in particular: It occurs through an ease of styling and maintenance of the hair after rinsing, and by a contribution to the volume and lightness at the dry hair level.
To do this, for a long time, use has been made of cationic polymers which, because of their strong affinity for capillary fibre which is anionic in nature, will have a persistent effect on the hair. Nevertheless, this phenomenon can lead to product deposits that are too significant: The feel of the hair becomes laden, unpleasant; the hair becomes stiff and there is an inter-fibre adhesion which affects styling.
A new generation of products has recently been developed to overcome these disadvantages. It is based on comb structured (meth)acrylic copolymers. The use of these products for hair care was described in documents EP 1 632 508 A1 and EP 2 168 991 A1. It will be apparent that their use in a shampoo formulation allows not only an improvement in its styling effect, but also facilitates its elimination after rinsing with water.
The expression “(meth)acrylic comb copolymer” is intended to designate a copolymer consisting of a skeleton that is essentially linear and of a (meth)acrylic type on which are grafted at least 2 side segments consisting of at least one “macromonomer”. The term “marcromonomer” refers to a water-soluble polymer or copolymer having at least one terminal group with an unsaturated ethylene function.
In the case of products developed for hair care and described in documents EP 1 632 508 A1 and EP 2 168 991 A1, this macromonomer is of the hydroxyl methacrylate or methoxy polyethylene glycol type (MPEG or MAMPEG methacrylate). In summary, the comb copolymers described in these two documents are the result of the synthesis between a first anionic monomer which can be (meth)acrylic acid, and an alkoxy or hydroxy polyakylene glycol macromonomer with the formula R—(EO)n—R′, with:                EO designating ethylene oxide and n being an integer between 3 and 300,        R designating an unsaturated polymerizable function such as the methacrylate function,        R′ representing hydrogen or a carbon radical with from 1 to 30 carbon atoms.        
In these two documents will be noted all the importance given to the specific macromonomers MPEG550 and MPEG2000, methoxypolyethylene glycol methacrylate with a mean molar mass by weight equal to 550 g/mol and 2,000 g/mol respectively.